iHOT-12 item analysis: correlations between individual items and overall score within and across time points

The main aim of this study was to analyze correlations between individual international hip outcome tool 12 (iHOT-12) items and overall iHOT-12 score within and across timepoints. A retrospective multicenter hip arthroscopy registry was queried for patients from January 2014 to October 2023 with completed iHOT-12 reports. Pearson coefficient analysis was used to identify correlations between individual iHOT-12 items and overall iHOT-12 score at each timepoint and between preoperative individual iHOT-12 items and postoperative overall iHOT-12 scores. Validity, reliability, and responsiveness of the iHOT-12 were analyzed at each timepoint. Within timepoints, correlations ranged in strength from fair (preoperative maintain fitness level, r = 0.52, P < .00001) to excellent (5-year hip pain after activity, r = 0.93, P < .00001). Correlations increased in strength over time. Across timepoints, correlations ranged in strength from no correlation (2-year maintain fitness level, r = -0.001, P = 0.94) to poor (6-month pushing or lifting heavy objects, r = 0.31, P < .00001). Correlations decreased in strength over time. No ceiling or floor effects were exhibited. The Cronbach alpha for the baseline, 6-month, 1-year, 2-year, and 5-year timepoints were 0.87, 0.96, 0.95, 0.96, and 0.97, respectively. Cohen's d values at 6 months, 1 year, 2 years, and 5 years were 1.19, 1.43, 1.71, and 1.58, respectively. Within timepoints, hip pain after activity had the strongest correlations to overall iHOT-12 score. Across timepoints, correlations between preoperative individual iHOT-12 items and postoperative overall iHOT-12 score were poor and weakened over time, suggesting similar long-term postoperative iHOT-12 scores among both high- and low-scoring preoperative patients. The iHOT-12 demonstrated good validity, reliability, and responsiveness at all timepoints.